Nevertheless, if you're among the lucky few currently rocking an octa-core GT-i9500-model Samsung Galaxy S4, you might be interested to see that a pre-rooted (and also pre-release) firmware is now available for download over at the XDA forums. As ever, the package can be flashed through the ODIN desktop utility, and you'll do so at your own risk. But pull it off and you'll have full, unrestricted access to that shiny new unreleased handset of yours.
More details and download instructions can be found over at the source link. It should go without saying that you shouldn't attempt to flash this onto the other Galaxy S4, the more common, Snapdragon 600-fuelled GT-i9505.